On Feb. 9, 1988, U.S. Pat. No. 4,724,400, entitled "Linear Amplifier" was issued in the name of G. G. Luettgenau to TRW Inc. (the "400 patent"). Such patent is treated herein solely as a publication.
The '400 patent shows and describes a microwave splitter-combiner apparatus comprising a cylindrical stack of vertically superposed circular metallic plates defining within the stack an upper divider waveguide or cavity and a lower combiner waveguide or cavity. Each such cavity comprises a pair of vertically spaced metallic walls and a chamber between and bounded by such walls and providing a passage through which microwaves propagate, the chamber being essentially in the form of a horizontal cylindrical disc. In the divider waveguide, the microwaves travel through its cylindrical disc chamber from its center radially outward while, in the combiner waveguide, such travel in its chamber is radially inward towards the center of the chamber. Both of the cavities have metallic wall portions bounding the cavity in which are concentric ridges and valleys formed by milling of a thick plate providing that wall surface.
Disposed on a plate member providing a top closure for the mentioned stack is a set of twenty r.f. amplifier operating units. The twenty units are equiangularly spaced in carousel fashion around the top of such member in respective radial planes which are vertical and pass through the vertical axis of the stack.
Each of such twenty r.f. amplifier units is coupled to the splitter waveguide by an input coaxial connector and to the combiner waveguide by an output coaxial connector. In the operation of the apparatus, high frequency electromagnetic energy is fed to the splitter waveguide's center, travels therefrom radially outward through the waveguide's chamber to the twenty input connectors and is then fed upward by them to the twenty amplifiers which operate in parallel to amplify such energy. The amplified energy is then fed via the twenty output connectors to points in the combiner waveguide's chamber which are radially outward of the chamber's center. From those points the energy travels as waves radially inward through the chamber to its center to there be combined and provide an amplified output from the apparatus.
In the apparatus of the '400 patent, the divider and combiner cavities have between them a single intermediate plate constituted of metal which is continuous in the plate's thickness dimension from the plate's surface bounding the divider cavity to the plate's surface bounding the combiner cavity.